The thumb screw is a very old torture tool that was used in ancient medieval Europe. It’s a very simple, easily disposable plastic vice, sometimes with many protruding screws on the inside surfaces. The fingers of victims, fingers, thumbs, or even toes were firmly placed into the vice and gently crushed. The thumb screw was also used to brutally torture prisoners’ large toes. Torture techniques such as these are vividly depicted in the medieval masterpieces by Michelangelo – The Arch of Triumph and The Last Supper.
These days, thumb screws aren’t usually used anymore. Instead, we have what are called “thumb nuts” – small metal cylinders (usually brass) with numerous nuts and bolts. We can tighten and loosen nuts and bolts using a wrench. But because thumb screws are so loose and malleable, they tend to break off and become lost in pockets and crevices. This makes replacing them quite difficult and dangerous – especially if you’re not sure what type of wrench you need.
Today, the most recommended type of thumb screw are the fully threaded types. These types have been standardized by the American Professional Woodturner’s Association (APWA). Although they’re not as popular as they used to be, they’re just as strong and just as convenient. They come in three different lengths: mini, regular and extended. And like all screw devices, they’re either completely threaded (type b) or have a slightly tapered threads (type c).
Mini thumb screws are most often used in pliers, screwdriver tools and similar devices. Their threads are slightly smaller than the standard type, so they fit tightly without gaps. You can use one spade head of this size in a very tight spot without the worry of it coming out. Spade head versions can be purchased at hardware stores or office supply specialty shops. Mini screwdrivers that feature a tapered head are also sometimes called “thumb grinders.”
The standard types, type I, are known by the name “threaded screwdrivers.” They’re usually equipped with a tapered head that can fit into tight places that other types of screws can’t. Because they’re tapered and their threads are bigger than those of type of screws, they tend to work more slowly. Some models, however, are equipped with small serrated teeth on their screw shafts to aid in getting into very small nooks and crannies. You can only find these models in larger commercial equipment stores.
Finally, the last type of thumb screw is the fully threaded variety. They’ve become somewhat obsolete in today’s world, but they can be found if you look in the right places. These types of screws often come with a serrated edge on one or both sides, which can help with getting a good fit. The cost is higher than the other two, but they provide better protection against wear and tear and provide the most versatility when it comes to installing screws. Fully threaded screws are often used on industrial equipment, such as free-standing machines and heavy machinery, but they may also be used for installation purposes on home repair and beauty equipment.
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